Constant-resistance electron-discharge device



W. C. WHITE.

CONSTANT RESISTANCE ELECTRON DISCHARGE DEVICE. APPLICATION FILED OCT 31. 1917.

Patented Oct. 3, 1922.

Current Potential LNVETTtO'P Z William .WhICe,

Patented ct. 1922.

WILLIAM C. WHITE, OF SCHENECTAIDY, NEW YORK, ASSIGNOR 'IO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Application filed October 3 1, 1917. Serial No. 199,565.

To all whom it may concern:

Be it known that I, IVILLIAM C. WHITE, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Constant- Resistance Electron-Discharge Devices, of which the following is a specification.

My present invention relates to electron discharge devices and has particular reference to the resistance characteristics of such devices.

It has been discovered thatthe current which will flow through an electron discharge device comprising an incandescent cathode and an anode enclosed in a highly evacuated envelope will, between certain limits, vary approximately as the 3/2 power of the applied voltage. In other words, the apparent resistance of such a device varies with the voltage applied to it. In some cases this characteristic is objectionable, as for example, when such a device is included in a measuring circuit which comprises other resistance. In such a case the relation between current and voltage in the circuit will be a complex one and a calibration will be necessary to determine this relation.

The object of my invention is to overcome this disadvantage by constructing andarranging an electron discharge device in such a way that the current therethrough will vary directly as the applied voltage between certain well defined limits.

In carrying my invention into effect I provide a third electrode in the device in the form of a grid which is preferably located between cathode and anode. Upon this grid I impress a definite positive potentlal with respect to the cathode, the value of this positive potential depending upon the construction of the device. In some cases I have found that the desired result may be obtained merely by connecting the grld to the positive end of the cathode.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. The invention itself however Wlll best be understood by reference to the following description taken in,connect1 on w th the accompanying drawing 1n which Fig. 1 shows diagrammatically a circuit connect on which may be employed in utilizing my lnvention, and Fig. 2 shows the current-voltage characteristics of an ordinary high vacuum electron discharge device and one which is operated in accordance with my inventlon.

As indicated in Fig. 1 an electron discharge device 1 comprises a cathode 2, an anode 3 and a grid shaped electrode 4 enclosed in a highly evacuated envelope 5. The cathode 2 is provided with the usual battery 6 for heating it to incandescence and the grid 4 is given a definite positive potential with respect to the cathode 2 by means of a battery 7. In some cases the construction of the device may be such that the desired result may be obtained by merely connecting the grid I to the positive end of the cathode. The curve A of Fig. 2 represents the relation between current and voltage in the usual two electrode high vacuum electron discharge device. Above a certain point the device has a working range over which the current varies substantially as the 3/2 power of the applied voltage while below that point, that is, at low voltages, there is no well defined relation between current and voltage. Above the working range over which the current varies as the 3/2 power of the applied voltage a point not shown on the curve will be reached at which all of the electrons emitted from the cathode are useful in carrying current and further increase in voltage will have no effect on the current. Curve B represents the relation which may be obtained between current and voltage in a device which is arranged in the manner indicated in Fig. 1. It will be seen that this curve is substantially a straight line between the limits given. In other words, between these limits the current varies directly as the applied potential and this relation holds over a wide range between very low voltages and voltages approaching the saturation voltage.

If it is desired to measure an alternating potential it will be apparent that the arrangement shown in Fig. 1 afi'ords a convenient means for making such a measurement. The alternating potential which is to be measured may be applied from the primary 10 of the transformer 11 to the secondary 8 which is included in circuit with the cathode 2 and anode 3 and a direct current measuring instrument 9. Since the current in 9 varies directly as the voltage in 8 the average value of the latter can quickly be determined from the reading of 9.

While I have described my invention with respect to one particular use therefor, I do not wish to be limited to the particular embodiment shown as it will be apparent that it may be utilized in many other organiza tions than the one shown and described without departing from the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electron discharge device comprising an electron emitting cathode, an anode and a grid enclosed in a highly evacuated receptacle, the parts being so related and the grid having impressed thereon such a o tential with respect to that of the cathode that the current between cathode and anode over a definite working range extending ing an electron emitting cathode, an anode and a grid enclosed in an evacuated envelope the parts being so related to each other and the grid being connected to the cathode in such a way that the apparent-resistance between cathode and anode is constant over a definite Working range of potential extending from a low potential to a potential near the saturation potential.

3. An electron discharge device comprising an electron emitting cathode, an anode and a grid enclosed in an evacuated envelope and a connection between cathode and grid whereby the grid has impressed thereon a definite potential with respect to the cathode, this potential being so chosen that the current between cathode and anode will vary directly with the potential applied between cathode and anode over a definite working range extending from a low potential to a potential near the saturation potential.

4. An electron discharge device comprising an electron emitting cathode, an anode and a grid enclosed in an evacuated envelo 3e and a connection between cathode and grid whereby the grid has impressed thereon a definite potential with respect to the cathode, this potential being so chosen that the apparent resistance between cathode and anode is constant over a definite Working range of potential extending from a low potential to a potential near the saturation potential.

In witness whereof, I have hereunto set my hand this 30th day of October, 1917.

WILLIAM C. WHITE. 

